The present invention relates in general to a locking assembly for a print wheel and, more particularly, to an assembly adapted for detachably connecting a print wheel of the daisy type to a motor shaft of a printing device having means for advancing a sheet of paper past the print wheel to effect printing thereon. The assembly is arranged within a carriage for tilting the print wheel away from the advancing means for replacement of the print wheel while returning to its position adjacent the advancing means during operation of the printing device.
A print wheel of the daisy type is generally constructed of a central hub which is removably coupled to the motor shaft of the driving mechanism for the print wheel and includes a plurality of pedals or radially extending spokes which carry the various character elements at its radial extremities in circumferentially spaced positions about the print wheel. Print wheels or daisies of this type may be utilized in a variety of applications. For example, print wheels may be used in series printers which are associated with communication terminals, computer output devices and other printing applications in the data processing field.
One important consideration in mounting a print wheel of the daisy type is the manner in which the print wheel may be removed from the rotary drive mechanism. Removability and/replacement of the print wheel is particularly important since the print wheel is subjected to a substantial battering force by the hammer of the printing device. In addition, it is desirable, particularly in typewriter applications, to permit removability or replacement of the print wheel so as to allow for selection of a particular style or type by merely changing print wheels. Thus, the ability to rapidly change the print wheel provides the same printing device with a full range of typing capabilities, for example, mathematical type notations, symbols and the like.
In accordance with the prior art, there is disclosed in U.S. Pat. No. 4,314,770 a detachable connection assembly for removably securing a print wheel to a rotary drive mechanism. The prior art assembly is generally constructed of a free floating plate spring biased adjacent a flange which is secured to a motor shaft of a rotary drive mechanism. The print wheel is provided with an upper hook-shaped shoulder and a pair of lower hook-shaped shoulders arranged in triangular relationship for engaging the lateral edges of the free floating plate. In this regard, as the plate is biased towards the flange, the print wheel is secured to the assembly by compressing the hook-shaped shoulders between the free floating plate and the flange. Such prior art assembly suffers from a number of notable disadvantages inherent in its construction. Specifically, it is highly desirable that the print wheel be connected directly to the motor shaft to promote direct rotation of the print wheel so as to prevent intermittent slipping which would otherwise cause intermittent misalignment of the various character elements with the paper to be printed on. In this regard, the prior art assembly does not achieve such results due to the print wheel being secured to a free floating plate.
Accordingly, it can be appreciated that there is an unsolved need for a locking assembly for a print wheel of the daisy type which facilitates the removability and/or replacement thereof in connection with a motor shaft of a rotary drive mechanism.